Device, system, and method of monitoring fax relay

ABSTRACT

Device, system, and method of monitoring fax relay. An apparatus for measuring Quality of Service (QoS) of Fax over Internet Protocol (FoIP) calls includes: a FoIP packet monitoring module to monitor in real-time Internet Protocol (IP) network streams exchanged between a FoIP emitter device and a FoIP receiver device; a FoIP equipment evaluator to evaluate real-time performance of at least one of: the FoIP emitter device, and the FoIP receiver device; and a FoIP call QoS evaluator to evaluate in real time a FoIP call QoS quality of a FoIP communication between said FoIP emitter device and said FoIP receiver device.

FIELD

The present invention relates to the field of facsimile communication.

BACKGROUND

Facsimile communication, commonly referred to as fax communication, mayinclude telephonic transmission of a scanned document to a remoteterminal over a telephone line. For example, a printed document may bescanned at a first fax terminal, which generates a bitmap graphic imagethat corresponds to the content of the scanned document. The data of thebitmap graphic image may then be transmitted by using a fax modem over atelephone line to a second, remote, fax terminal, which may convert thereceived data into an image and may print that image on paper.

A fax relay system may be used for transferring facsimile calls in realtime over a packet- based network. For example, a fax relay system mayutilize Fax over Internet Protocol (FoIP) communications, which may bein accordance with Recommendation T.38 of the Standardization Sector ofthe International Telecommunication Union (ITU).

SUMMARY

The present invention may include, for example, devices, systems, andmethods for monitoring the Quality of Service (QoS) of fax relay,particularly in Fax over Internet Protocol (FoIP) systems, as well asperforming diagnostics for such systems and detecting problems therein.

In accordance with the present invention, an apparatus for measuringQuality of Service (QoS) of Fax over Internet Protocol (FoIP) calls mayinclude: a FoIP packet monitoring module to monitor in real-timeInternet Protocol (IP) network streams exchanged between a FoIP emitterdevice and a FoIP receiver device; a FoIP equipment evaluator toevaluate real-time performance of at least one of: the FoIP emitterdevice, and the FoIP receiver device; and a FoIP call QoS evaluator toevaluate in real time a FoIP call QoS quality of a FoIP communicationbetween said FoIP emitter device and said FoIP receiver device.

In accordance with the present invention, the FoIP packet monitoringmodule may include: a FoIP stream error detectors sub-unit to detect inreal time FoIP stream errors; and a T.30 diagnostics measurementsub-unit to measure in real time T.30 diagnostics measurements.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a FoIP stream collision detector todetect collisions of FoIP streams exchanged between said FoIP emitterdevice and said FoIP receiver device; wherein at least one of said FoIPequipment evaluator and said FoIP call QoS evaluator, takes into accountoutput generated by the FoIP stream collision detector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a FoIP T.30 control stream under-runerror detector to detect a possible under-run error of a T.30 controlsignal transmitter of said FoIP emitter device or of said FoIP receiverdevice; wherein at least one of said FoIP equipment evaluator and saidFoIP call QoS evaluator, takes into account output generated by the FoIPT.30 control stream under-run error detector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a fax image stream transfer errordetector to detect possible over-run and under-run errors of fax imagetransmitter of FoIP receiver.

In accordance with the present invention, at least one of said FoIPequipment evaluator and said FoIP call QoS evaluator, takes into accountoutput generated by the fax image stream transfer error detector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a FoIP call establishment problemdetector to detect problems in FoIP call establishment; and a FoIPstream violation detector to detect a FoIP stream violation; wherein atleast one of said FoIP equipment evaluator and said FoIP call QoSevaluator, takes into account output generated by at least one of theFoIP call establishment problem detector and the FoIP stream violationdetector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include a FoIP T.30 control stream error detectorto detect errors of FoIP T.30 control streams; and the T.30 diagnosticsmeasurement sub-unit may include a T.30 call establishment problemdetector to detect a problem in T.30 call establishment between saidFoIP emitter device and said FoIP receiver device; wherein at least oneof said FoIP equipment evaluator and said FoIP call QoS evaluator, takesinto account output generated by at least one of the FoIP T.30 controlstream error detector and the T.30 call establishment problem detector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a FoIP packet loss detector to detectFoIP packet loss; and an Inter-Packet Delay (IPD) detector to detect along IPD in a FoIP stream sent between said FoIP emitter device and saidFoIP receiver device; wherein at least one of said FoIP equipmentevaluator and said FoIP call QoS evaluator, takes into account outputgenerated by at least one of the FoIP packet loss detector and the IPDdetector.

In accordance with the present invention, the T.30 diagnosticsmeasurement sub-unit may include: a fax image data error detector tocheck fax image data errors; wherein at least one of said FoIP equipmentevaluator and said FoIP call QoS evaluator, takes into account outputgenerated by the fax image data error detector.

In accordance with the present invention, the T.30 diagnosticsmeasurement sub-unit may include: a fax image data rate estimator toestimate an actual data rate of fax image data sent by said FoIP emitterdevice; wherein at least one of said FoIP equipment evaluator and saidFoIP call QoS evaluator, takes into account output generated by the faximage data rate estimator.

In accordance with the present invention, the T.30 diagnosticsmeasurement sub-unit may include: an incompatible FoIP call detector todetect a FoIP call which may be unsupported by at least one of: saidFoIP emitter device and said FoIP receiver device; and a T.30 signalflow violation detector to detect FoIP packets irrelevant to a currentT.30 phase; wherein at least one of said FoIP equipment evaluator andsaid FoIP call QoS evaluator, takes into account output generated by atleast one of the incompatible FoIP call detector and the T.30 signalflow violation detector.

In accordance with the present invention, the FoIP stream errordetectors sub-unit may include: a T.30 Training Check Frame (TCF) streamunder-run error detector to detect a possible under-run error of a T.30TCF transmitter of FoIP receiver; and the T.30 diagnostics measurementsub-unit comprises a T.30 TCF error detector to detect a T.30 TCF errorin a T.30 stream sent from said FoIP emitter device to said FoIPreceiver device; wherein at least one of said FoIP equipment evaluatorand said FoIP call QoS evaluator, takes into account output generated byat least one of the T.30 TCF stream under-run error detector and theT.30 TCF error detector.

In accordance with the present invention, the T.30 diagnosticsmeasurement sub-unit may include: a timeout detector to detect at leastone of: a no-stream FoIP timeout, and a T.30 phase timeout; wherein atleast one of said FoIP equipment evaluator and said FoIP call QoSevaluator, takes into account output generated by the timeout detector.

In accordance with the present invention, the T.30 diagnosticsmeasurement sub-unit may include: a fax call parameters detector todetect one or more parameters of a fax call between said FoIP emitterdevice and said FoIP receiver device; wherein at least one of said FoIPequipment evaluator and said FoIP call QoS evaluator, takes into accountoutput generated by the fax call parameters detector.

In accordance with the present invention, the FoIP equipment evaluatormay include: an evaluation unit to evaluate in real time a performanceof the IP network during a FoIP call, and to evaluate in real time aperformance of at least one of: the FoIP emitter device, and the FoIPreceiver device; wherein the evaluation unit takes into account anoutput generated by at least one of: said FoIP stream error detectorssub-unit, and said T.30 diagnostics measurement sub-unit.

In accordance with the present invention, the apparatus may include aFoIP call Quality of Service (QoS) evaluator to evaluate a QoS of a FoIPcall; wherein the FoIP call QoS evaluator may include: a Figure of Merit(FOM) estimator, to estimate a FOM value associated with said FoIP call;and an overall FoIP call result evaluator, to estimate a quality of FoIPcall taking into account an output generated by at least one of: the FOMestimator, and said FoIP equipment evaluator.

In accordance with the present invention, the apparatus may be or mayinclude a FoIP gateway.

In accordance with the present invention, the apparatus may be or mayinclude a Session Border Controller (SBC).

In accordance with the present invention, the apparatus may be or mayinclude a computerized platform external to said FoIP emitter device,external to said FoIP receiver device, external to a FoIP gateway, andexternal to a Session Border Controller (SBC).

In accordance with the present invention, a device may be operablyassociated with the apparatus, and the device may include: a datareceiver to receive, from said apparatus, real-time reports of monitoredFoIP streams; and an evaluator to cumulatively evaluate, based on anaggregation of said real-time reports, an overall quality of a FoIPservice.

In accordance with the present invention, the evaluator may evaluateperformance of at least one of: a FoIP emitter device, a FoIP receiverdevice, and an IP network path through which FoIP packets are sentbetween the FoIP emitter device and the FoIP receiver device.

In accordance with the present invention, a method for measuring Qualityof Service (QoS) of Fax over Internet Protocol (FoIP) calls may include:monitoring in real-time Internet Protocol (IP) network streams exchangedbetween a FoIP emitter device and a FoIP receiver device; evaluatingreal-time performance of at least one of: the FoIP emitter device, andthe FoIP receiver device; and evaluating in real time a FoIP call QoSquality of a FoIP communication between said FoIP emitter device andsaid FoIP receiver device; wherein monitoring in real-time IP networkstreams exchanged between a FoIP emitter device and a FoIP receiverdevice comprises: detecting in real time FoIP stream errors, andmeasuring in real time T.30 diagnostics measurements. The method may beimplementable by utilizing at least a hardware component.

In accordance with the present invention, the method may beimplementable by utilizing a hardware device selected from the groupconsisting of: a FoIP gateway; a Session Border Controller (SBC); acomputerized platform external to said FoIP emitter device, external tosaid FoIP receiver device, external to a FoIP gateway, and external to aSession Border Controller (SBC).

The present invention may provide other and/or additional benefitsand/or advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

For simplicity and clarity of illustration, elements shown in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements may be exaggerated relative to otherelements for clarity of presentation. Furthermore, reference numeralsmay be repeated among the figures to indicate corresponding or analogouselements. The figures are listed below.

FIG. 1 is a schematic block-diagram illustration of a prior art FoIPsystem able to monitor analog fax signals;

FIG. 2 is a schematic block-diagram illustration of another prior artFoIP system able to monitor analog fax signals;

FIG. 3 is a schematic block-diagram illustration of a local side of aprior art FoIP system able to monitor analog fax signals;

FIG. 4A is a schematic block-diagram illustration of a FoIP systemcapable of monitoring the Quality of Service (QoS) of a FoIP service, inaccordance with the present invention;

FIG. 4B is a schematic block-diagram illustration of FoIP QoS monitor,in accordance with the present invention;

FIG. 5 is a schematic block-diagram illustration of a FoIP gatewayincluding a FoIP QoS monitor, in accordance with the present invention;

FIG. 6 is a schematic block-diagram illustration of a communicationsystem including a Session Border Controller (SBC) which incorporatesone or more a FoIP QoS monitors, in accordance the present invention;

FIG. 7 is a schematic block-diagram illustration of an SBC incorporatinga FoIP QoS monitor, in accordance with the present invention; and

FIG. 8 is a schematic block-diagram illustration of a communicationsystem in which a FoIP Session Experience Manager (SEM) operatesexternally to FoIP gateways and externally to SBC devices, in accordancewith the present invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of some embodiments.However, it will be understood by persons of ordinary skill in the artthat some embodiments may be practiced without these specific details.In other instances, well-known methods, procedures, components, unitsand/or circuits have not been described in detail so as not to obscurethe discussion.

Applicant has realized that conventional systems and methods, whichattempt to monitor performance of fax relays, are either unsuitable forFoIP systems or suffer from multiple deficiencies, as detailed hereinwith reference to FIGS. 1-3.

Reference is made to FIG. 1, which is a schematic block-diagramillustration of a prior art FoIP system 199 able to monitor analog faxsignals. Particularly, system 199 may utilize fax call measurements forverification of transferring fax calls over a network, by monitoringanalog fax signals exchanged between communicating fax terminals andFoIP gateways.

System 199 may include, for example, a local fax terminal 10, a localPublic Switched Telephone Network (PSTN) 20, a local service gateway100, an Internet Protocol (IP) network 30, a remote gateway 40, a remotePSTN 50, and a remote fax terminal 60. Local fax terminal 10 may beconnected to local PSTN 20, which may be connected to local servicegateway 100. Similarly, remote fax terminal 60 may be connected toremote PSTN 50, which may be connected to remote gateway 40. Localservice gateway 100 may communicate over IP network 30 with remotegateway 40. Optionally, instead of utilizing remote gateway 40 andremote fax terminal 60, an IP-aware or IP capable fax terminal (referredto as “IP fax”) 70 may be used.

During a fax relay call in system 199, local service gateway 100 mayexchange analog fax signals 21 with local fax terminal 10. Local servicegateway 100 may further exchange FoIP packets 31 with remote gateway 40or with IP fax 70.

In accordance with a prior art method of operation, analog fax signals21 may be transmitted by local fax terminal 10 and then by local servicegateway 100. Analog fax signals 21 may optionally be recorded by a faxsignal recorder 110 in their original sampling wave form, or analog faxsignals 21 may be demodulated in real-time (e.g., utilizing a dedicatedhardware component) and then recorded by fax signal recorder 110 in apre-defined (e.g., proprietary) signal data log form. The recordedsignals may be analyzed by a fax signal analyzer 111, which may beimplemented by using as a software component in a computer workstation.Fax signal analyzer 111 may produce one or more fax metrics 112 whichmay be partially indicative of the quality of the fax call, for example,the quality of the fax image or the call result (e.g., success orfailure). Fax metrics 112 may be stored, logged and/or monitored, at acalling fax side and/or at an answering fax side. Optionally, faxmetrics 112 may be used to monitor or verify the fax relay operation ofa gateway (e.g., service gateway 100).

Applicant has realized that the monitoring method utilized by system 199may not be suitable for most FoIP service providers, for example,because a FoIP service may not have physical access to analog faxsignals 21.

Reference is made to FIG. 2, which is a schematic block-diagramillustration of a prior art FoIP system 299 able to monitor analog faxsignals. The components of system 299 may be generally similar to thecomponents of system 199 of FIG. 1. System 299 may utilize fax callmonitoring, for example, by capturing a network packet exchange betweenFoIP gateways, and then analyzing offline the captured streams ofpackets. For this purpose, system 299 may include a T.38 recorder 210able to capture network data in real time. The recorded network streamsmay be examined off-line by a T.38 analyzer 211 (e.g., a softwaremodule), which may extract the relayed fax image data and may log faxmetrics 212 (e.g., the decoded fax image and the call result).Optionally, a user may analyze the captured and recorded network packetsby utilizing a suitable software program (e.g., Wireshark).

Applicant has realized that although the method utilized by system 299may partially assist some FoIP gateway vendors and some IP-fax vendors,such method may be highly problematic for FoIP service providers. Forexample, the recording of T.38 streams and their offline analysis maynot be suitable for a system that operates in real-time.

Applicant has further realized that for simultaneous transfer ofmultiple channels of FoIP calls, system 199 of FIG. 1 and/or system 299of FIG. 2 may require extremely large storage capacity and computationalresources in order to capture FoIP calls, decode the fax image streams,and analyze the signal flows.

Reference is made to FIG. 3, which is a schematic block-diagramillustration of a local side of a prior art FoIP system 399 able tomonitor analog fax signals. The components of system 399 may begenerally similar to the components of system 199 of FIG. 1. System 399may utilize fax call monitoring, for example, by real-time faxmeasurements at a FoIP gateway.

System 399 may utilize real-time reporting of fax relay status data 310by local service gateway 100 (e.g., a FoIP gateway) to a network server.When transferring fax calls, local service gateway 100 may report, forexample, the current T.30 status, the modulation and demodulationparameters, a number of fax pages successfully relayed over the IPnetwork, and/or other data.

System 399 may analyze the T.30 signal and the FoIP stream internally bylocal service gateway 100. Applicant has realized that system 399 maysuffer from multiple deficiencies. For example: FoIP status reporting bylocal service gateway may be incomplete for Quality of Service (QoS)purposes and/or for diagnostics purposes. Additionally, access togateway FoIP status reporting may be denied to the FoIP serviceprovider, or may be only partially authorized (e.g., allowed only ingateway debug mode). Furthermore, fax call analysis and reporting by aFoIP gateway may utilize proprietary formats or proprietary datastructures which may depend on the particular FoIP gateway vendor, andmay further vary depending on the FoIP gateway version of the sameprovider, and thus a FoIP service provider using different FoIP gatewaysmay have difficulties to measure fax QoS.

Reference is made to FIG. 4A, which is a schematic block-diagramillustration of a FoIP system 499 capable of monitoring the Quality ofService (QoS) of a FoIP service, in accordance with the presentinvention. System 499 may analyze FoIP streams of two communicatinggateways, for example, a local service gateway 400 and a remote gateway40. Service gateway 400 may be a FoIP gateway in accordance with thepresent invention.

In contrast with prior art system 299 of FIG. 2, system 499 of thepresent invention may not require FoIP packet recording. Rather, insystem 499, all the necessary fax QoS measurements may be performed inreal time by a FoIP QoS monitor 415. For example, FoIP QoS monitor 415may analyze the FoIP streams exchanged between service gateway 400 andremote gateway 40 (or IP fax 70) over IP network 30. FoIP QoS monitor415 may further perform fax QoS measurements, may diagnose or evaluatethe FoIP operation of service gateway 400, may diagnose or evaluate theFoIP operation of remote gateway 40, may diagnose or evaluate the FoIPoperation of IP fax 70, and/or may diagnose or evaluate the FoIPoperation of IP network 30. Upon completion of a monitored FoIP call,FoIP QoS monitor 415 may report the determined FoIP operation metrics,for example, the fax call result and diagnostics 416 of FoIP operationto an upper-level application or for another component or server, forcumulative measurements and/or diagnostics.

Optionally, FoIP QoS monitor may receive and handle the fax relay statusreported by service gateway 400. In such case, FoIP QoS monitor 415 mayachieve improved evaluation results for example, with regard to theperformance of the analog interface of service gateway 400, or withregard to the performance of a switched network (e.g., PSTN 20)connected between service gateway 400 and fax terminal 10.

FoIP QoS monitor 415 may perform non-intrusive fax call datameasurements which may be partially or fully compliantly with ITU-TRecommendation E.459 and/or with ITU-T Recommendation E.460

Reference is made to FIG. 4B, which is a schematic block-diagramillustration of FoIP QoS monitor 415 showing components and modulesthereof, in accordance with the present invention. Main modules of FoIPQoS monitor 415 may include, for example, a FoIP packet monitor module440, a FoIP equipment performance evaluator 470, and a FoIP call QoSevaluator 480. FoIP packet monitor module 440 may include, for example,a FoIP stream error detectors unit 450, a T.30 diagnostics measurementsunit 460, and/or a FoIP/T.30 state machine 469. FoIP stream errordetectors unit 450 may include components or modules to perform faxrelay packet measurements in order to detect possible problems relatedto fax relay packet transfer; such components or modules may include,for example: a FoIP call establishment problem detector 451; a FoIPstream violation detector 452; a FoIP T.30 control stream error detector453; a FoIP stream collision detector 454; a FoIP packet loss detector455; a long Inter-Packet Delay (IPD) detector 456; a FoIP T.30 controlstream under-run error detector 457; a T.30 Training Check Frame (TCF)stream under-run error detector 458; and/or a fax image stream transfererror detector 459. Additionally, FoIP stream error detectors unit 450may include other detectors of FoIP stream errors. T.30 diagnosticsmeasurements unit 460 may include components or modules to perform T.30diagnostics measurements in order to detect possible FoIP/T.30 problemsand to measure fax call parameters; such components or modules mayinclude, for example, a T.30 call establishment problem detector 461, anincompatible FoIP call detector 462, a T.30 signal flow violationdetector 463, a FoIP timeout detector 464, a T.30 TCF error detector465, a fax image data error detector 466, a fax call parameters detector467, a fax image data rate estimator 468. Additionally, T.30 diagnosticsmeasurements unit 460 may perform other diagnostics measurements. FoIPequipment performance evaluator 470 may include components or modules toevaluate a performance of equipment providing FoIP call; such componentsor modules may include, for example, a FoIP emitter performanceevaluator 471, a FoIP receiver performance evaluator 472, a IP networkperformance evaluator 473, and/or, optionally, a PSTN performanceevaluator 474. FoIP call QoS evaluator 480 may include components ormodules to evaluate an overall FoIP call quality such components ormodules may include, for example, a Figure of Merit (FOM) estimator 481,and/or an overall FoIP call result evaluator 482. FoIP QoS monitor 415may include some or all of components 451-482, which may be implementedusing software modules and/or hardware components.

FoIP call establishment problem detector 451 may detect problems in FoIPcall establishment. For example, FoIP QoS monitor 415 may bepre-programmed or may be configured (e.g., by an upper-levelapplication) in accordance with FoIP capabilities of one or moreparticular communicating FoIP gateways. Such upper-level application maybe, for example, a component or module responsible for allocation andmanagement of FoIP QoS monitor 415. FoIP call establishment problemdetector 451 may detect, for example, conflicts between FoIPcapabilities of a first gateway initiating a FoIP session and FoIPcapabilities of a second gateway confirming the transition to FoIPoperation. Additionally or alternatively, FoIP call establishmentproblem detector 451 may detect an error of a one-way FoIP stream,caused by absent or malformed FoIP stream from one of the communicatinggateways.

FoIP stream violation detector 452 may verify the packets transferredover IP network 30 between communicating gateways. FoIP stream violationdetector 452 may detect, for example, one or more of the following FoIPstream violations: (1) primary fax packet overflow relative to maximumprimary frame size capability of a destination gateway; (2) datagramoverflow relative to maximum datagram size capability of a destinationgateway; (3) malformed packets; and/or (4) incorrect FoIP encoding.Violation (1) and/or violation (2) may be detected, for example, bychecking the FoIP packets according to gateway capabilities. Violation(3) may be detected, for example, by verifying a packetization ofprimary packet frame and error correction data contributing to a totalpacket length. Violation (4) may be detected by checking the FoIPindicator packets and data packets according to FoIP encoding rules.

FoIP T.30 control stream error detector 453 may detect errors in FoIPstreams transferring T.30 control packets. T.30 control packets mayrelay T.30 indicators or low rate T.30 data, for example, V.21 data, orV.34 control channel data, or V.8 messages, or V.34-rate information.Applicant has realized that, for example, the following T.30-relatederrors may affect the FoIP QoS: (a) High-level Data Link Control (HDLC)frame errors, for example, incorrect frame length, absence of HDLCaddress, and/or absence of HDLC control fields; (b) transferringfacsimile control fields that may be unsupported by a FoIP gateway; (c)T.30 final frame re-ordering; and/or (d) missing T.30 indicator packets.FoIP T.30 control stream error detector 453 may detect T.30 streamerrors (a) and (b), for example, by checking the HDLC frame headers; maydetect error (c) by verifying the HDLC frame sequence; and may detecterror (d) by checking transmission of T.30 indicator packets accordingto selected FoIP protocol.

FoIP stream collision detector 454 may detect FoIP stream collisions.Applicant has realized that facsimile communication over packetnetwork(s) may be significantly affected by excessive delays of packetstreams in the packet network(s). Various reasons may cause the delay ofFoIP streams, for example, (A) FoIP call establishment delay, (B) FoIPgateway processing delay, (C) passing FoIP packets over multiple networknodes, and/or (D) FoIP operation in tandem with other gateways workingin FoIP or in voice-band-data modes. The T.30 command re-transmissionscaused by IP network delay (or by normal fax procedures), and furtheraffected by the IP network delay, may result in FoIP stream collisions.The FoIP stream collisions may affect the FoIP gateway operation (e.g.,of service gateway 400 or remote gateway 40), or may cause analog signalcollision in a link between a FoIP gateway (e.g., service gateway 400 orremote gateway 40) and a fax terminal (e.g., fax 10 or remote fax 60).FoIP stream collision detector 454 may detect these types of FoIP streamcollisions, for example, by checking the correspondence of FoIP streamsreceived from the IP network to the current T.30 phase of the FoIPemitter or the FoIP receiver. The current T.30 phase may be derived byFoIP/T.30 state machine 469 from previously-received streams, in bothdirections.

FoIP packet loss detector 455 may check the sequence number of acurrently-received FoIP packet, relative to the sequence number ofpreviously-received FoIP packet(s), and may take into account the FoIPerror correction data transferred in according with FoIP capabilities ofthe communicating gateways. FoIP packet loss detector 455 may measure(e.g., independently from each other) the packet loss of T.30 controlstreams sent by FoIP emitting gateway, the packet loss of T.30 controlstreams sent by FoIP receiving gateways, and/or the packet loss of faximage streams sent by FoIP emitting gateway. These measurements ofpacket loss for different streams may be utilized as diagnostics ofdifferent network paths, and may be used to identify source reasons ofpossible fax failure or quality degradation.

Long IPD detector 456 may detect long inter-packet delays. Whenforwarding the fax relay packets to FoIP QoS monitor 415 for QoS anddiagnostics measurements, an upper-level application may attach thetimestamps, source identifier, and/or other attributes or meta-data ordescriptors of the fax relay packets. The FoIP IPD may be measured byusing timestamps. The delays between consequent data packets of the sameFoIP stream may contribute to IPD measurements; whereas the delays ofHDLC frame data relative to previous HDLC frames may be excluded. TheFoIP IPD measurements may include, for example, IPD averaging,determining the maximal IPD, computing the FoIP packet jitter (IPDvariation), or other IPD-related calculations. Long IPD detector 456 maymeasure (e.g., independently of each other) the IPD of T.30 controlstreams sent by FoIP emitting gateway, the IPD of T.30 control streamssent by FoIP receiving gateways, and the IPD of fax image streams sentby FoIP emitting gateway. These measurements of FoIP inter-packet delaysfor different streams may be utilized as diagnostics of differentnetwork paths, and may be used to identify source reasons of possiblefax failure or quality degradation.

FoIP T.30 control stream under-run error detector 457 may detectpossible under-run errors of T.30 control streams. In order to avoid anexcessively-long processing delay of T.30 commands and responses, a FoIPgateway (e.g., service gateway 400 or remote gateway 40) may start theT.30 control data transmission toward a linked fax terminal (e.g. fax 10or remote fax 60) before the FoIP gateway receives a complete HDLC framefrom IP network 30, based on an assumption that the HDLC octets that arecurrently lacking for transmission may arrive in a pre-configured ormeasured IPD time. However, if the lacking octets of HDLC frame areabnormally delayed in the network, the real-time T.30 controltransmitter of FoIP gateway (e.g., service gateway 400 or remote gateway40) may suffer from under-run errors. Accordingly, control streamunder-run error detector 457 may detect (e.g., independently of eachother) the under-run errors related to T.30 control data sent by FoIPemitting and/or FoIP receiving gateways.

T.30 TCF stream under-run error detector 458 may detect T.30 TCF streamunder-run errors. For example, an under-run error of T.30 TCF stream mayhappen if a FoIP gateway starts the TCF data transmission toward the faxterminal before that FoIP gateway receives the complete TCF data fromthe IP network, while assuming that the TCF octets that are currentlylacking for transmission may arrive in a pre-configured or measured IPDtime. If the lacking TCF octets are abnormally delayed in the network,the real-time TCF transmitter of the FoIP gateway may suffer fromunder-run error. T.30 TCF stream under-run error detector 458 may detectpossible under-run errors of T.30 TCF streams, for example, by checkingdelays between currently-received TCF data packets andalready-transferred TCF data.

Fax image stream transfer error detector 459 may detect over-run andunder-run errors of fax image streams. For example, fax image streamerror detector 459 may utilize a FoIP receiver capability of maximumbuffer size (e.g., FaxMaxBuffer) which may indicate the maximum numberof octets that may be stored on the FoIP receiver before an overflowcondition occurs. To detect a possible overflow, fax image streamtransfer error detector 459 may compare the difference between theamount of fax image data received from the IP network (FaxLengRx) andthe amount of fax image data that may be transmitted to a fax terminalby FoIP receiver (FaxLengTx) for a measured time interval relative tothe maximum buffer size of FoIP receiver (FaxMaxBuffer). For example, anover-run error may be detected if (FaxLengRx-FaxLengTx) is greater thanFaxMaxBuffer.

Under-run errors of fax image streams may further be detected, eventhough such under-run errors of fax image streams may be less criticalfor FoIP transfer, because such errors may be corrected by a FoIPreceiver gateway (for example, by HDLC flag transmission between HDLCframes of ECM fax image, or by T.4 filling between scan lines of T.4non-ECM fax image). However, particularly for some FoIP gateways whichmay be incapable of filling the T.4 non-ECM fax image, fax image streamtransfer error detector 459 may detect possible under-run errors of faximage streams. Fax image stream transfer error detector 459 may comparethe difference between the amount of fax image data received from the IPnetwork (FaxLengRx) for a measured time interval, and the amount of faximage data that may be transmitted to a fax terminal by FoIP receivergateway (FaxLengTx) for the same time interval. An under-run error maybe detected, for example, if (FaxLengTx−FaxLengRx) is greater thanFaxLengIPD, wherein FaxLengIPD may indicate, for example, the amount offax image data transmitted for a pre-configured inter-packet delay.

T.30 call establishment problem detector 461 may detect T.30 callestablishment problems. Applicant has realized that in spite ofautomatic T.30 call establishment initiated by fax terminals, the FoIPgateways, due to various problems or conditions, may enter or force amanual T.30 call setup. For example, in case of V.34 fax calls, themanual call establishment of “4 bis b” may significantly increase theduration of fax session relative to the duration of fax session withautomatic T.30 call setup of “4 bis a”. Some FoIP gateways may block theV.8 ANSam signal or T.30 called (CED) fax tone. As a result, a callingfax terminal started in automatic call establishment mode with sendingthe calling (CNG) fax tone may not detect the automatic call procedurefrom the answer fax side, due to blocking of the answer tone CED orANSam by the FoIP gateway. Accordingly, T.30 call establishment problemdetector 461 may detect the manual call establishment “4 bis b”, forexample, by detecting V.8 call indicator (CI) message packets, and bydetecting the absence of CED/ANSam packets from the answer fax side inpresence of CNG packets from the calling fax side.

Incompatible FoIP call detector 462 may detect, for example, (a)conflicts of V.8 Negative Acknowledge (NAK) to V.8 Facsimile ApplicationProfile (FAP) both relayed over the FoIP protocol, (b) T.30 controlframes of Non-Standard facilities Set-up (NSS) and Non-Standardfacilities Command (NSC), (c) complex T.30 operation, and/or (d) othertypes of FoIP call incompatibilities.

Incompatibility problem (a) may be a pure FoIP problem which may occur,for example, if a V.8 NAK message received from the answer side gatewayindicates an absence of compatible mode with fax modes indicated in V.8FAP message received from the calling fax side gateway. Incompatibilityproblem (b) may be detected if T.30 NSS or NSC frames are relayed inspite of blocking or destroying non-standard capabilities of answer faxby FoIP gateway(s). Because a FoIP protocol, for example T.38 protocol,supports only a standard operation mode, a gateway may prevent thenon-standard capabilities to be transferred end-to-end from the answerfax to the calling fax. Nevertheless, the calling fax may start in anon-standard mode, for example, if this fax is configured for onlysecure fax transmission. Therefore, NSS or NSC frames detected in FoIPstreams may be indicative of incompatible fax call. Furthermore,incompatibility problem (c) may be detected, for example, as some faxcall options which may be normal for communication over switchednetworks, may be problematic for FoIP calls. For example, T.30 procedureinterrupts, secure fax, duplex operation, Frame Not Valid (FNV), andsome other T.30 capabilities may be not supported or not fully supportedby the FoIP gateway(s). Accordingly, detection of such call options mayassist in diagnosing the cause for FoIP call failures.

T.30 signal flow violation detector 463 may detect T.30 signal flowviolations. For purposes of FoIP gateway diagnostics, T.30 signal flowviolation detector 463 may verify the T.30 signal flow at the FoIPgateway by analyzing T.30 control streams exchanged in both directions:the FoIP streams sent by the diagnosed FoIP gateway toward the remotegateway (or towards the remote IP fax) over the IP network, and the FoIPstreams sent by the remote gateway (or by the remote IP fax) over the IPnetwork toward the diagnosed FoIP gateway. During a successful FoIPcall, each diagnosed FoIP gateway is expected to consequently pass theT.30 phases or states, wherein a current T.30 phase or state may bederived by FoIP/T.30 state machine 469 from the previously-receivedstreams in both directions. Accordingly, T.30 signal flow violationdetector 463 may follow the T.30 gateway states, and may detect FoIPpackets or FoIP streams which may be irrelevant to a current T.30 phaseor to previously-received FoIP packets.

FoIP timeout detector 464 may detect FoIP timeouts. Applicant hasrealized that for the purposes of diagnostics and of FoIP QoS monitoringmanagement, it may be useful to measure and/or monitor the no-streamtimeout and/or the T.30 phase timeout.

The no-stream timeout may be detected in one FoIP direction (e.g., fromFoIP receiver to FoIP emitter, or from FoIP emitter to FoIP receiver),or in both communication directions. Detection of a bi-directionalno-stream timeout may be a sufficient reason for an upper-levelapplication to close the FoIP monitoring of the fax call, and optionallyto also close the FoIP call. The threshold of no-stream timeout maydepend, for example, on the current T.30 phase.

The T.30 phase timeout may be detected regardless of the no-streamtimeout. For example, the FoIP gateways may exchange over the IP networkmultiple attempts of T.30 pre-/post-message signals, such that no-streamtimeout may not occur, but an excessively long pre-/post-messageprocedure may inform about serious problems in the FoIP gateway, or inthe gateway analog signal interface, or in other elements of the FoIPsetup.

T.30 TCF error detector 465 may detect T.30 TCF errors. In contrast tonon-intrusive fax call data measurements (e.g., in accordance with ITU-TRecommendations E.459/E.460), in which a reason of TCF fallback may beunimportant or undetected, the present invention may utilize T.30 TCFerror detector 465 to determine the reason/or and the source gatewaycausing T.30 TCF fallbacks. For example, T.30 TCF error detector 465 maycheck, may monitor and/or may verify that (a) the T.30 DCS transferpreceding T.30 TCF is normal, (2) that the length of TCF zeroes streamlays in the range defined by T.30, (3) that measured TCF inter-packetdelay is supported by typical gateways, and/or (4) that there is nocollision of DCS/TCF stream with a stream from FoIP receiver.

Fax image data error detector 466 may detect fax image data errors. Innon-intrusive fax call data measurements (e.g., in accordance with ITU-TRecommendations E.459/E.460), in which a reason of fax imageretransmission or rejection may be unimportant or undetected, thepresent invention may utilize fax image data error detector 466 tomonitor the fax image streams, to monitor a result of fax page transfer,and to determine the reason and/or the source causing the fax imageretransmission or rejection. The result of fax page transfer may bemeasured without verification of the fax image data, for example, bychecking only a content of T.30 post-message response frame sent by FoIPreceiver. Furthermore, fax image data error detector 466 using theresult of monitoring fax image streams and the result of fax pagetransfer may determine the reason and/or the source causing the faximage retransmission or rejection. The fax image stream monitoring maybe based on the fax image error check, and optionally, may use the faximage demodulation quality reported by the FoIP emitting gateway.

Optionally, fax image data may be transferred with incorporation ofError Correction Mode (ECM). Accordingly, fax image data error detector466 may perform error check by verifying the headers of transferred T.4Facsimile Coded Data (FCD) frames, FCD frame lengths, and by detectingReturn to Control for Partial page (RCP) frames.

Optionally, in transfers of non-ECM fax image data, to satisfy thereal-time requirements, fax image data error detector 466 may perform areduced error check or a shortened or partial version of the error checkprocess. For example, in a demonstrative minimal configuration, insteadof full decoding of the fax image, fax image data error detector 466 maycheck the availability of fax image data and Return-To-Control (RTC)pattern. Furthermore, when verifying non-ECM fax image data, fax imagedata error detector 466 may check the image scan line data.

Fax call parameters detector 467 may detect, for example, a type of faxcall, an exchanged value of fax data rate, a total number of fax pagestransferred over the IP network, a number of pages transferred atmaximal fax rate, the numbers of pages transferred at lower fax rates,the numbers of pages transferred error-free, the numbers of pagestransferred with errors.

Fax image data rate estimator 468 may estimate an actual fax data rate.In contrast to fax call data measurements in switched networks, wherethe V.34 primary channel data signaling rate is extracted from MPhsignal (e.g., in accordance with ITU-T Recommendation E.460), the actualdata rate of V.34 FoIP transfer may be unavailable, for example, becausethe MPh content may not be relayed over the IP network. According toITU-T Recommendation T.38, a maximal data rate acceptable by T.38receiving gateway may be exchanged over the IP network. However, as forthe data rate of T.38 emitting gateway, it is required only to be lessor equal to the exchanged rate of the receiver. For estimation of actualdata rate of ECM fax transfer, fax image data rate estimator 468 maytake into account the total number of fax page data octets and FCDframes relayed over the IP network during the fax page image stream. TheECM fax data rate computed may be an approximate rate, since the HDLCprotocol corresponds to asynchronous data transmission. Actual data rateof non-ECM fax image may be computed more accurately. Estimated actualV.34 fax image data rate may be used in FoIP call QoS evaluator 480.Furthermore, fax image data rate estimator 468 may help, for example, indiagnostics of V.34 and non-V.34 fax image transfer problems.

Figure of Merit (FOM) estimator 481 may estimate FOM metrics. Accordingto ITU-T Recommendation E.458, the performance of end-to-end facsimiletransmission may be evaluated by using the FOM metrics defined throughseven different transaction types, ranging from type 1 (a perfect faxcall) to type 7 (an incomplete fax call). In accordance with the presentinvention, Figure of Merit (FOM) estimator 481 may monitor and analyzeFoIP streams exchanged between FoIP emitter and FoIP receiver, and mayestimate the FOM metric of FoIP calls.

In accordance with the present invention, FoIP QoS monitor 415 or adedicated module or component thereof, for example, FoIP equipmentperformance evaluator 470 may evaluate the performance of, or the QoSthat is provided by, one or more of: a FoIP emitter, a FoIP receiver, anIP network path from FoIP emitter to FoIP QoS monitor 415, and/or an IPnetwork path from FoIP receiver to FoIP QoS monitor.

FoIP equipment performance evaluator 470 may generate an indicator valuefor diagnostics of FoIP equipment. For example, an indicator value of“0” may indicate that diagnostics are absent (e.g., for equipment whichcannot be evaluated in current FoIP session); an indicator value of “1”may indicate error-free operation; an indicator value of “2” mayindicate operation with warnings; an indication value of “4” mayindicate operation with errors; and indicator value of “6” (e.g., thesum of value 2 and value 4) may indicate operation with both warningsand errors. Other suitable values may be used, and other suitablerepresentation methods may be used. Optionally, the diagnostics error orwarning level may depend on end-to-end FOM metric(s). For example, T.30problems detected at FoIP gateway may be considered as “errors” forseverely erroneous fax calls or for failed fax calls, but may beconsidered as “warnings” for successful fax calls.

FoIP equipment performance evaluator 470, for example, may utilize (a)ITU-T defined fax QoS measurements, (b) FoIP stream measurements, (c)T.30 diagnostics measurements, and/or (d) logic decisions fordiagnostics of FoIP equipment. The particular logic or decision-makingalgorithm about the source of FoIP problems may be tailored per FoIP QoSmonitor 415, but may take into account one or more properties orconsiderations as discussed herein. Optionally, FoIP QoS monitor 415using demodulation quality and demodulation parameters reported by FoIPgateway may evaluate the performance 474 of a switched network (e.g.,PSTN 20) connected between service gateway 400 and fax terminal 10.

In accordance with the present invention, some types of problemsdetected in FoIP stream measurements may be considered definitely asFoIP gateway problems. This may include, for example, FoIP callestablishment problems, FoIP stream violations, errors in FoIP streamstransferring T.30 control packets, over-run errors of fax image streams,and most errors detected during T.30 diagnostics measurements. Incontrast, some detected problems may be considered definitely as thenetwork problems, for example, FoIP packet loss, high FoIP packet jitteror long IPD. Additionally, some detected problems may be attributed tofaulty operation of FoIP gateways and the IP network, for example, FoIPstream collisions or under-run errors of FoIP streams.

A determination of the source of TCF or fax image transfer problem (forexample, whether the problem source is the FoIP emitter or the FoIPreceiver) may take into account the availability and amount of errorsdetected in TCF or fax image streams, as well as other aspects of FoIPand T.30 operations. As a demonstrative example, the discussion hereinmay describe a decision-making process about the FoIP source gatewayresponsible for regular G3 fax rate fallback which happened during aT.30 pre-message procedure. The decision (e.g., out of four possiblecases) may depend on the TCF transferring method, as the T.30 TCF may belocally generated or may be transferred over the IP network.

In a first case, the TCF is locally generated by FoIP receiver butrejected by the fax terminal (the FoIP emitter in response on T.30 DCSreceived the T.30 FTT frame). Accordingly, the suitable decision may beto assign error level 2 (operation with warnings) to the FoIP receiver.

In a second case, the TCF is locally generated and confirmed by FoIPreceiver, but the FoIP emitter relays in response on T.30 CFR (andinstead of fax image) a new DCS frame, thereby indicating a fallback ofmodulation system or/and of fax rate. Accordingly, the suitable decisionmay be to assign error level 2 (operation with warnings) to the FoIPemitter.

In a third case, a good error-free TCF stream sent by FoIP emitter isrejected by FoIP receiver. Accordingly, the suitable decision may be toassign error level 2 (operation with warnings) to the FoIP receiver.

In a fourth case, the FoIP emitter sends a too short TCF stream orerroneous TCF stream, or fails to send TCF. Accordingly, the suitabledecision may be to assign the error level 2 (operation with warnings) tothe FoIP emitter.

The decisions in these four cases may further depend on fax maximum ratecapabilities of the FoIP gateways. For example, if the DCS frame sent bythe FoIP emitter indicates a bit rate above the maximum fax ratecapability of the FoIP receiver, FoIP QoS monitor 415 may avoidassigning the error/warning level to the FoIP receiver.

Optionally, FoIP QoS monitor 415 may be used for diagnostics of faxterminal and of switched network between the FoIP gateway and the faxterminal Optional utilization of FoIP gateway status reporting of faxdemodulation quality and parameters may assist in improveddiscrimination of FoIP problem sources, for example, FoIP gateway analoginterface imperfections or switched network impairments.

FoIP QoS monitor 415 may generate proprietary reports indicating the faxQoS measurements, the FoIP stream measurements, the T.30 diagnosticsmeasurements, and/or the diagnostics of FoIP equipment. In ademonstrative embodiment of the present invention, color indicatorsand/or evaluation values may be set to indicate an overall FoIP callresult, by FoIP QoS monitor 415 or by a dedicated module or componentthereof, for example, an overall FoIP call result evaluator 482. Forexample, a black color and/or an evaluation value of “0” may indicatethat the fax call did not start. A green color and/or an evaluationvalue of “1” may indicate that a successful fax call passed with FOMequaling 1 (perfect fax call) and with diagnostics level not greaterthan 2 (operation with warnings) for all elements of FoIP equipment. Ayellow color and/or an evaluation value of “2” may indicate that asuccessful fax call passed with FOM equaling 1 and with diagnosticslevel greater than 2 for one or more elements of FoIP equipment, or thatsuccessful fax call passed with FOM greater than 1 but smaller than 7(incomplete fax call). A red color and/or an evaluation value of “3” mayindicate an incomplete or incompatible fax call (corresponding to FOMvalue of 7). A gray color and/or an evaluation value of “4” may indicatethat a one-way fax call ended without relaying T.30 signals from callingor answering fax side. Other suitable colors or evaluation values may beused.

Additionally to a final report with overall FoIP call result, FoIP QoSmonitor 415 may report intermediate results, for example, every fax pagetransferred, or every pre-defined time interval (e.g., every 30 or 60seconds).

Due to the specific nature of the FoIP service relative to the faxservice over switched networks, some fax call data measurements whichare defined in ITU-T Recommendation E.459 and/or in ITU-T RecommendationE.460 may not be required. Further, FoIP call data measurements inaccordance with the present invention may utilize new types ofmeasurements that are not defined in ITU-T Recommendation E.459 and/orITU-T Recommendation E.460, and which may not necessarily be relevant tofax service over switched networks.

Reference is made to FIG. 5, which is a schematic block-diagramillustration of a FoIP gateway 500 comprising a FoIP QoS monitor 515, inaccordance with the present invention. FoIP gateway 500 may exchangeT.30 signals 504 with a connected fax terminal 10 over a switchednetwork 20 and through an analog signal interface 501. FoIP gateway 500may exchange FoIP packets 31 over IP network 30 with a remote gateway oran IP fax. A packet interface 502 may be used for physical packetexchange over IP network 30 and, for example, for addition and deletionof network protocol headers during transmission and reception of FoIPpackets by a fax relay unit 503. Fax relay unit 503 may process thesampled T.30 signals 504 and the fax relay packets, for example, T.38packets 511 and 512. FoIP QoS monitor 515 may inspect the T.38 packetsexchanged in two directions: T.38 packets 511 sent by fax relay unit 503toward IP network 30, and T.38 packets 512 received from IP network 30and forwarded to fax relay unit 503. On experience of fax call, FoIP QoSmonitor 515 may report the call result and diagnostics 516 to anupper-level application for cumulative measurements and diagnostics.This report may be transferred, for example, over packet interface 502and a local network and/or IP network 30. Optionally and additionally tothe final report, FoIP QoS monitor 515 may report intermediate results,for example, every fax page transferred, or every pre-defined timeinterval (e.g., every 30 or 60 seconds).

Embedding or integration of FoIP QoS monitor 515 into FoIP gateway 500may be implemented by one or more software modules and/or hardwarecomponents. Such integration may be beneficial when an original gatewaydoes not support (partially or entirely) the fax QoS and diagnosticsmeasurements. This may help to avoid undesired changes in fax relay unit503 which may be responsible for fax relay.

The present invention may be used in conjunction with a Session BorderController (SBC). For example, an SBC may optionally be used in a VoIPnetwork, to exert control over the signaling and typically also themedia streams involved in setting up, conducting, and/or tearing downcalls. The SBC may enforce security, Quality of Service (QoS), and/oradmission control mechanism over the VoIP sessions.

Reference is made to FIG. 6, which is a schematic block-diagramillustration of a communication system 699 comprising a Session BorderController (SBC) 600 which incorporates one or more a FoIP QoS monitors615, in accordance the present invention. Multiple gateways, forexample, gateway 1 (620) through gateway K (629) of a service providermay perform fax communications over an IP network 33. Each activechannel of a service gateway may exchange the analog fax signals with afax terminal over a PSTN 20, and may exchange the FoIP packets with oneof remote gateways 40 (or a remote IP fax) over the IP networks 33 and30. In system 699, some service gateways may be used as local gatewaysconnected to SBC 600 over IP network 33, and other service gateways mayoperate as remote gateways connected to SBC 600 over IP network 30. Allthe calls of the service gateways 620-629 may be controlled by SBC 600.For example, SBC 600 may be able to control one or more fax callssimultaneously. In order to monitor N fax relay calls simultaneously(wherein N may be equal to or greater than one), SBC 600 may allocateand may manage N modules and/or instances of FoIP QoS monitor 615. Onexperience of each fax call, SBC 600 may report the call result anddiagnostics 616 to an upper-level application for cumulativemeasurements and diagnostics. This report may be transferred, forexample, over local or IP network 33. Optionally and additionally to thefinal reports, SBC 600 may report intermediate results, for example,every fax page transferred, or every pre-defined time interval (e.g.,every 30 or 60 seconds).

Reference is made to FIG. 7, which is a schematic block-diagramillustration of an SBC 700 incorporating a FoIP QoS monitor 715, inaccordance with the present invention. SBC 700 may exchange packets 32with FoIP gateways of a service provider over IP network 33, and mayexchange packets 31 with remote gateways over IP network 30. Packetinterfaces 701 and 702 may serve for physical packet exchange over theIP networks and, for example, for addition and deletion of IP headersduring packet transmission and reception. SBC unit 710 may be capable oftransferring a fax call, and may include, for example, a fax sessioncontroller 719 and FoIP QoS monitor 715. Fax session controller 719 mayprocess the packets 711-714 received from to IP networks 33/30 overpacket interfaces 701/702. The packet processing by the fax sessioncontroller 719 may include, for example, forwarding the T.38 packets 711as packets 713; forwarding packets 714 as the T.38 packets 712;transcoding the T.38 packets 711 into packets 713; transcoding packets714 into T.38 packets 712; securely encrypting/decrypting, and otheroperations. FoIP QoS monitor 715 may inspect the T.38 packets 711 and712. On experience of a fax call, FoIP QoS monitor 715 may report thecall result and diagnostics 716 to an upper-level application forcumulative measurements and diagnostics. This report may be transferred,for example, over packet interface 701 and the IP network 33. Optionallyand additionally to the final report, FoIP QoS monitor 715 may reportintermediate results, for example, every fax page transferred, or everypre-defined time interval (e.g., every 30 or 60 seconds).

SBC 700 may allocate more than one SBC units to control and monitor upto N fax sessions simultaneously (wherein N is greater than one). Forexample, SBC unit 1 (710) and other units up to SBC unit N (790) may be,for example, identical or may have different fax session controllers719. SBC 700 may allocate the FoIP QoS monitors 715 dynamically, forexample, allocating one FoIP QoS monitor 715 per every detected faxcall; or allocating statically, according to a maximum number of faxcalls which may be controlled simultaneously.

In accordance with the present invention, FoIP QoS monitoring may beperformed externally to a FoIP gateway and/or externally to an SBCdevice, for example, at a workstation or a computer or a network serveror other computing platform.

Reference is made to FIG. 8, which is a schematic block-diagramillustration of a communication system 899 in which a FoIP SessionExperience Manager (SEM) 815 operates externally to FoIP gateways andexternally to SBC devices, in accordance with the present invention. Forexample, FoIP SEM 815 may operate within a network server 800, mayaccumulate the fax relay call results and diagnostics from FoIP QoSmonitors of one or more SBCs 830 controlling one or more servicegateways or/and from FoIP QoS monitors of other service gateways 820 notcontrolled by SBC. Additionally, SBCs 830 and/or service gateways 820may communicate with network server 800 over IP network 33. FoIP SEM 815may report the overall metrics and diagnostics 816 of FoIP calls tonetwork server 800. Each one of SBCs 830, and/or each one of servicegateways 820, may include one or more FoIP QoS monitors 888 or othersimilar modules or components.

In real time, FoIP SEM 815 may perform cumulative fax data measurementswith reporting the primary metrics, for example, in accordance withITU-T Recommendations E.459/E.460. Such measurements may include, forexample, percentage of call completion; percentage of calls usingmaximum transmission rate; and/or percentage of calls having good imagequality. Additionally or alternatively, FoIP SEM 815 may calculate andreport the secondary metrics per ITU-T Recommendations E.459/E.460.Additionally or alternatively, FoIP SEM 815 may calculate and reportFoIP QoS metrics in accordance with the present invention.

In real time, FoIP SEM 815 may calculate cumulative diagnosticsmeasurements to evaluate the overall performance of FoIP serviceequipment. For example, FoIP SEM 815 may calculate and report percentageof fax calls impaired by service (local) gateways; percentage of faxcalls impaired by remote gateways or by remote IP faxes; and/orpercentage of fax calls impaired by the IP network(s).

In real time, FoIP SEM 815 may further analyze cumulative data oraggregated data received from multiple FoIP QoS monitors 888, and maydiagnose problems that were not necessarily detected and/or notnecessarily reported explicitly by FoIP QoS monitors 888. For example,sufficiently high percentage (e.g., greater than a threshold percentagevalue) of fax calls impaired by fax rate fallbacks and/or by fax imageerrors detected from FoIP gateways, may indicate on possible problems inswitched or ISDN networks over which the FoIP gateways exchange theanalog fax signals with connected fax terminals.

In real time, FoIP SEM 815 may analyze cumulative data and may resolve apossible ambiguity of the diagnostics generated by the multiple FoIP QoSmonitors 888. For example, some FoIP problems may be caused both by FoIPgateways and by fax terminals. However, a consistent presence of thesame FoIP problem at different fax terminals may indicate existence of aFoIP gateway problem (rather than a fax terminal problem). In contrast,presence of the same FoIP problem in communication with a particular faxterminal over different vendor FoIP gateways may indicate problems inthe fax terminal (and not in the FoIP gateways).

In real time, FoIP SEM 815 may analyze cumulative data to derive optimalconfiguration parameters of FoIP service gateways. In a first example,cumulative measurements of FoIP inter-packet delay (IPD) may be used toderive an optimal fax relay IPD configuration parameter of gateways. Alower IPD configuration parameter may help to improve theinteroperability of FoIP service gateways with different fax terminalsand different vendor FoIP gateways, and to reduce the gateway processingdelay and a total duration of FoIP call. Alternatively, a higher IPDconfiguration parameter may be applied for better tolerance of FoIPservice gateways to network jitter. In a second example, cumulativemeasurements of FoIP packet loss may be used to derive an optimal depthof FoIP error-correction data to configure the FoIP service gatewaysand/or to be negotiated with remote gateways.

The optimal or preferred configuration parameters of FoIP gateways,derived by FoIP SEM 815, may be loaded or transferred to servicegateways and/or to SBCs, automatically, manually (e.g., with the help ofFoIP service administrator), on-demand, at pre-defined time intervals,on an hourly or daily basis, in response to a triggering event, when apre-defined condition is met, or the like.

The present invention may be used in conjunction with fax relaytechnology, for example, for transferring facsimile calls in real timeover Internet Protocol (IP) networks. The present invention may be usedby systems operating in accordance with the Fax-over-IP (FoIP) protocol,for example, as standardized in ITU-T Recommendation T.38. The presentinvention may be used by network operators providing the FoIP service,who may desire to control the quality of fax calls relayed over the IPnetwork. The present invention may be used by systems which may alsoutilize ITU-T Recommendations E.450-E.454 and E.456-E.460, which definegeneral aspects of facsimile Quality of Service (QoS) on publicnetworks, measurement technology, fax call measurements, and cumulativemeasurements.

The present invention may include devices, systems, and methods of faxrelay Quality of Service (QoS), as well as diagnostics of types andsources of possible fax relay problems; which may be achieved byutilizing one or more real-time FoIP QoS monitors (or monitoringmodules).

The real-time FoIP protocol used by the FoIP QoS monitor may be astandard T.38 protocol, for example, the Internet Fax Protocol (IFP)transferred over TCP/IP, the IFP encapsulated in UDPTL transferred overUDP/IP, the IFP encapsulated in RTP transferred over UDP/IP, or anotherstandard T.38 protocol.

In some embodiments, for example, the real-time FoIP protocol used bythe FoIP QoS monitor may be the T.38 UDPTL encapsulated in RTPtransferred over UDP/IP, for example, as described in U.S. Pat. No.7,899,038, which is incorporated herein by reference in its entirety.

In some embodiments, for example, the real-time FoIP protocol used bythe FoIP QoS monitor may be an enhanced or extended or modified orimproved T.38 protocol or an equivalent or similar protocol, which maybe standard or proprietary.

In some embodiments, for example, the FoIP QoS monitor may analyze thereal-time FoIP streams from FoIP emitter gateway and FoIP receivergateway. To satisfy the real-time confinements, the FoIP QoS monitor maylimit the processing and analysis of the FoIP streams by the QoS anddiagnostics measurements; for example, the FoIP QoS monitor may avoid afull or partial decoding of relayed fax image data.

In some embodiments, for example, the FoIP QoS monitor may carry out thefax QoS and diagnostics measurements in real-time while avoiding faxsignal recording and/or while avoiding network packet recording.

In some embodiments, for example, the FoIP QoS monitor may perform theQoS measurements compliant to non-intrusive fax QoS measurements definedin ITU-T Recommendations.

In some embodiments, for example, the FoIP QoS monitor may optionallyuse the real-time FoIP status reports of a local or controlled gateway.

In some embodiments, for example, the FoIP QoS monitor may perform thediagnostics measurements to estimate the quality of operation ofcommunicating gateways, of the IP network, optionally, of fax terminals,and optionally, of the switched network.

In some embodiments, for example, the FoIP QoS monitor may diagnoseand/or may detect various problems of fax communication over the packetnetworks.

In some embodiments, for example, the FoIP QoS monitor may establish asource equipment responsible of degradation of fax relay QoS. Forexample, the problem may be attributed to (a) FoIP emitter, (b) FoIPreceiver, (c) network path from FoIP emitter to the FoIP QoS monitor,(d) network path from FoIP receiver to the FoIP QoS monitor, (e)optionally, calling fax terminal, (f) optionally, answering faxterminal, and/or (g) optionally, switched network.

In some embodiments, for example, the FoIP QoS monitor may be embeddedin a gateway, or in an SBC, or may be external to such devices, or maybe implemented within a network server or workstation or other computingplatform.

In some embodiments, for example, a fax relay quality of serviceapparatus may include a FoIP session experience manager, which may logand accumulate the FoIP QoS measurements reported by one or more FoIPQoS monitors. The FoIP session experience manager may perform overallQoS metrics of FoIP calls transferred by controlled gateways. The FoIPsession experience manager may perform cumulative diagnostics of faxrelay problems reported by one or more FoIP QoS monitors.

Some embodiments of the present invention may operate, and may monitorand/or evaluate FoIP QoS, without the need to record fax signals (e.g.,in their original sampling wave form), and/or without the need todemodulate (e.g., in real-time) analog fax signals and then record themby using a signal data log, and/or without the need to store recordedfax signals or copies of fax signals for subsequent off-line analysis ofsuch pre-recorded fax signals.

Some embodiments of the present invention may operate, and may monitorand/or evaluate FoIP QoS, without the need to record FoIP streams forsubsequent off-line analysis of such pre-recorded FoIP streams.

The terms “local” and “remote” may be considered as formal terms. Theterm “local” may be equivalent to “one side”, and the term “remote” maybe equivalent to “other side”. Any two FoIP devices communicating overthe IP network may be considered as a pair of a local FoIP device and aremote FoIP device.

Discussions herein utilizing terms such as, for example, “processing,”“computing,” “calculating,” “determining,” “establishing”, “analyzing”,“checking”, or the like, may refer to operation(s) and/or process(es) ofa computer, a computing platform, a computing system, or otherelectronic computing device, that manipulate and/or transform datarepresented as physical (e.g., electronic) quantities within thecomputer's registers and/or memories into other data similarlyrepresented as physical quantities within the computer's registersand/or memories or other information storage medium that may storeinstructions to perform operations and/or processes.

Some embodiments may take the form of an entirely hardware embodiment,an entirely software embodiment, or an embodiment including bothhardware and software elements. Some embodiments may be implemented byusing a pre-installed application, a download-able application, anapplication available for purchase and/or for downloading from an“application store” or a “virtual market” for smartphone applications,an application residing as machine-readable code or program on anarticle or storage medium (e.g., CD-ROM, flash drive, memory stick, USBflash drive, non-transitory medium or storage medium), or the like.

Functions, operations, components and/or features described herein withreference to one or more embodiments, may be combined with, or may beutilized in combination with, one or more other functions, operations,components and/or features described herein with reference to one ormore other embodiments.

While certain features of some embodiments have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents may occur to those skilled in the art. Accordingly, theclaims are intended to cover all such modifications, substitutions,changes, and equivalents.

What is claimed is:
 1. An apparatus for measuring Quality of Service(QoS) of Fax over Internet Protocol (FoIP) calls, the apparatuscomprising: a FoIP packet monitoring module to monitor in real-timeInternet Protocol (IP) network streams exchanged between a FoIP emitterdevice and a FoIP receiver device; a FoIP equipment evaluator toevaluate real-time performance of at least one of: the FoIP emitterdevice, and the FoIP receiver device; and a FoIP call QoS evaluator toevaluate in real time a FoIP call QoS quality of a FoIP communicationbetween said FoIP emitter device and said FoIP receiver device.
 2. Theapparatus of claim 1, wherein the FoIP packet monitoring modulecomprises: a FoIP stream error detectors sub-unit to detect in real timeFoIP stream errors; and a T.30 diagnostics measurement sub-unit tomeasure in real time T.30 diagnostics measurements.
 3. The apparatus ofclaim 2, wherein the FoIP stream error detectors sub-unit comprises: aFoIP stream collision detector to detect collisions of FoIP streamsexchanged between said FoIP emitter device and said FoIP receiverdevice; wherein at least one of said FoIP equipment evaluator and saidFoIP call QoS evaluator, takes into account output generated by the FoIPstream collision detector.
 4. The apparatus of claim 2, wherein the FoIPstream error detectors sub-unit comprises: a FoIP T.30 control streamunder-run error detector to detect a possible under-run error of a T.30control signal transmitter of said FoIP emitter device or of said FoIPreceiver device. wherein at least one of said FoIP equipment evaluatorand said FoIP call QoS evaluator, takes into account output generated bythe FoIP T.30 control stream under-run error detector.
 5. The apparatusof claim 2, wherein the FoIP stream error detectors sub-unit comprises:a fax image stream transfer error detector to detect possible over-runand under-run errors of fax image transmitter of FoIP receiver. whereinat least one of said FoIP equipment evaluator and said FoIP call QoSevaluator, takes into account output generated by the fax image streamtransfer error detector.
 6. The apparatus of claim 2, wherein the FoIPstream error detectors sub-unit comprises: a FoIP call establishmentproblem detector to detect problems in FoIP call establishment; and aFoIP stream violation detector to detect a FoIP stream violation;wherein at least one of said FoIP equipment evaluator and said FoIP callQoS evaluator, takes into account output generated by at least one ofthe FoIP call establishment problem detector and the FoIP streamviolation detector.
 7. The apparatus of claim 2, wherein the FoIP streamerror detectors sub-unit comprises a FoIP T.30 control stream errordetector to detect errors of FoIP T.30 control streams; wherein the T.30diagnostics measurement sub-unit comprises a T.30 call establishmentproblem detector to detect a problem in T.30 call establishment betweensaid FoIP emitter device and said FoIP receiver device; wherein at leastone of said FoIP equipment evaluator and said FoIP call QoS evaluator,takes into account output generated by at least one of the FoIP T.30control stream error detector and the T.30 call establishment problemdetector.
 8. The apparatus of claim 2, wherein the FoIP stream errordetectors sub-unit comprises: a FoIP packet loss detector to detect FoIPpacket loss; and an Inter-Packet Delay (IPD) detector to detect a longIPD in a FoIP stream sent between said FoIP emitter device and said FoIPreceiver device; wherein at least one of said FoIP equipment evaluatorand said FoIP call QoS evaluator, takes into account output generated byat least one of the FoIP packet loss detector and the IPD detector. 9.The apparatus of claim 2, wherein the T.30 diagnostics measurementsub-unit comprises: a fax image data error detector to check fax imagedata errors; wherein at least one of said FoIP equipment evaluator andsaid FoIP call QoS evaluator, takes into account output generated by thefax image data error detector.
 10. The apparatus of claim 2, wherein theT.30 diagnostics measurement sub-unit comprises: a fax image data rateestimator to estimate an actual data rate of fax image data sent by saidFoIP emitter device; wherein at least one of said FoIP equipmentevaluator and said FoIP call QoS evaluator, takes into account outputgenerated by the fax image data rate estimator.
 11. The apparatus ofclaim 2, wherein the T.30 diagnostics measurement sub-unit comprises: anincompatible FoIP call detector to detect a FoIP call which may beunsupported by at least one of: said FoIP emitter device and said FoIPreceiver device; and a T.30 signal flow violation detector to detectFoIP packets irrelevant to a current T.30 phase; wherein at least one ofsaid FoIP equipment evaluator and said FoIP call QoS evaluator, takesinto account output generated by at least one of the incompatible FoIPcall detector and the T.30 signal flow violation detector.
 12. Theapparatus of claim 2, wherein the FoIP stream error detectors sub-unitcomprises a T.30 Training Check Frame (TCF) stream under-run errordetector to detect a possible under-run error of a T.30 TCF transmitterof FoIP receiver; wherein the T.30 diagnostics measurement sub-unitcomprises a T.30 TCF error detector to detect a T.30 TCF error in a T.30stream sent from said FoIP emitter device to said FoIP receiver device;wherein at least one of said FoIP equipment evaluator and said FoIP callQoS evaluator, takes into account output generated by at least one ofthe T.30 TCF stream under-run error detector and the T.30 TCF errordetector.
 13. The apparatus of claim 2, wherein the T.30 diagnosticsmeasurement sub-unit comprises: a timeout detector to detect at leastone of: a no-stream FoIP timeout, and a T.30 phase timeout; wherein atleast one of said FoIP equipment evaluator and said FoIP call QoSevaluator, takes into account output generated by the timeout detector.14. The apparatus of claim 2, wherein the T.30 diagnostics measurementsub-unit comprises: a fax call parameters detector to detect one or moreparameters of a fax call between said FoIP emitter device and said FoIPreceiver device; wherein at least one of said FoIP equipment evaluatorand said FoIP call QoS evaluator, takes into account output generated bythe fax call parameters detector.
 15. The apparatus of claim 1, whereinthe FoIP equipment evaluator comprises: an evaluation unit to evaluatein real time a performance of the IP network during a FoIP call, and toevaluate in real time a performance of at least one of: the FoIP emitterdevice, and the FoIP receiver device; wherein the evaluation unit takesinto account an output generated by at least one of: said FoIP streamerror detectors sub-unit, and said T.30 diagnostics measurementsub-unit.
 16. The apparatus of claim 1, comprising a FoIP call Qualityof Service (QoS) evaluator to evaluate a QoS of a FoIP call, wherein theFoIP call QoS evaluator comprises: a Figure of Merit (FOM) estimator, toestimate a FOM value associated with said FoIP call; and an overall FoIPcall result evaluator, to estimate a quality of FoIP call taking intoaccount an output generated by at least one of: the FOM estimator, andsaid FoIP equipment evaluator.
 17. The apparatus of claim 1, wherein theapparatus is a FoIP gateway.
 18. The apparatus of claim 1, wherein theapparatus is a Session Border Controller (SBC).
 19. The apparatus ofclaim 1, wherein the apparatus is a computerized platform external tosaid FoIP emitter device, external to said FoIP receiver device,external to a FoIP gateway, and external to a Session Border Controller(SBC).
 20. A device operably associated with the apparatus of claim 1,the device comprising: a data receiver to receive, from said apparatus,real-time reports of monitored FoIP streams; and an evaluator tocumulatively evaluate, based on an aggregation of said real-timereports, an overall quality of a FoIP service.
 21. The device of claim20, wherein the evaluator is to evaluate performance of at least one of:a FoIP emitter device, a FoIP receiver device, and an IP network paththrough which FoIP packets are sent between the FoIP emitter device andthe FoIP receiver device.
 22. A method for measuring Quality of Service(QoS) of Fax over Internet Protocol (FoIP) calls, the method comprising:monitoring in real-time Internet Protocol (IP) network streams exchangedbetween a FoIP emitter device and a FoIP receiver device; evaluatingreal-time performance of at least one of: the FoIP emitter device, andthe FoIP receiver device; and evaluating in real time a FoIP call QoSquality of a FoIP communication between said FoIP emitter device andsaid FoIP receiver device; wherein monitoring in real-time IP networkstreams exchanged between a FoIP emitter device and a FoIP receiverdevice comprises: detecting in real time FoIP stream errors, andmeasuring in real time T.30 diagnostics measurements; wherein the methodis implementable by utilizing at least a hardware component.
 23. Themethod of claim 22, wherein the method is implementable by utilizing ahardware device selected from the group consisting of: a FoIP gateway; aSession Border Controller (SBC); a computerized platform external tosaid FoIP emitter device, external to said FoIP receiver device,external to a FoIP gateway, and external to a Session Border Controller(SBC).